Directive receiver



ec. 31, 1935. W KAR I 2,026,359

' DIRECTIVE RECEIVER Filed April 50, 1932 2 Sheets-Sheet 1 g INVENTOR O-IllllP GREENLEAF WH\TTIER PICKARD ATTORNEY ec. 31, 1935. 5 w PlcKARD 2,026,359

' DIRECTIVE RECEIVER Filed April 30, 1932 2 Sheets-Sheet 2 INVENTOR GREENLEAF WH\TT\ER PICKARD ATTORNEY Patented Dec. 31, 1935 UNiTED srrss rATENT orrics DIRECTIVE RECEIVER Greenleaf Whittier Pickard, Newton Center,

Mass, assignor to Radio Corporation of America, a corporation of Delaware Application April 30, 1932, Serial No. 608,354

7 Claims. (Cl. 250-41) -Radio receivers, by means of which the direccontacts are imperfect, and often produce serious tion from which the signals to which the receiver noise as the loop is rotated. is tuned are coming may be ascertained, are An object of the present invention is to proknown in the art. These receivers, known herevide a directional receiver in which provision is tofore, in general comprise a signal absorption made to eliminate or overcome all of the above system which absorbs signal energy, the quantity defects. of which depends upon the physical position of Receivers of this type are often used under the absorption system relative to the source of conditions in which the operators time and signals, means for amplifying and/or rectifying thoughts are entirely taken up with other duties 1:) the signals, and means for indicating the intenand yet it is imperative that the operator know 10 sity of the signals absorbed and amplified and at all times the location of the source of signals rectified. In known devices of this type the abwith respect to his receiver. -A receiver having sorption system generally comprises what is an aural indicating means is in this case undeknown as the frame or loop aerial of my U. S. sirable since it requires the mental attention of Patent 876,998 which consists of one or more the operator in addition to the time necessary turns of wire on a form, which may be rotated to operate the receiver. For example, where the about its axis in such a manner as to place the receiver is located on an airship all of the above plane of the turns of wire at any desired angle conditions are present and in addition thereto with respect to a line through the loop and the noise level is so high that it is hard and even go through the signalling'source. This loop strucimpossible in some cases for the operator to loture is tuned to signal frequency by a variable Cate the direction of the source of signals by capacity connected therewith. The energy from means of an aural indicator. the loop o'r'frame aerial is transmitted to metal A specific object of the present invention is rings mounted on the shaft and insulated from to provide a receiver by means of which the poeach other and this energy is transferred by way sition of the signal source with respect to the of brushes to the amplifier. This structure is receiver will always beobvious to the operator necessary to permit rotation of the loop and to and in which the position of the source of signals prevent the leads between the terminals of the with respect to the receiver will be indicated by loop and the amplifier or detector from becoming either an aural or a visual indicator, as the 0p- 0 twisted or broken when the loop is rotated. crating conditions require. I have found that Usually an aural indicator is connected with the in general the ear responds to peak values of detector or with amplifiers, which are in turn sound, whereas galvanometers or other'visual connected with the detector. indicator in general respond to r. m. s. values. These receivers are in some respects satisfac- So marked is this differentiation that consistent tory, but in others are unsatisfactory. For exgalvanometer readings of signals may generally ample, the contacts between the brushes and be made in the presence of irregular disturbances. rings introduce capacity and sometimes high of such magnitude, as to the ear, completely impedances in the leads from the loop or demask the'signal. This is due to the fact that tector. These capacities and/or impedances vary the ear does not integrate sound over appreciabl\ 40 during rotation of the loop and thereby vary the intervals, which the galvanorneter does, and that amount of energy reaching the amplifiers from disturbances, such as static, ignition noise, etc., the loop so that the energy impressed on the rehave low r. m. s. value as compared with the sigceiver amplifier is not truly representative of nal, even if their peak values are much higher. the energy absorbed by the absorption system. A further object of the present invention is to Also, the capacities between the rings and brushes provide an arrangement whereby the energy from 45 may vary during rotation of the loopsufiiciently the loop is transmitted to the receiver without to affect the tune of the loop to such an extent the use of any contacting apparatus such as that the loop may be tuned to the signal in one rings and brushes, which have been heretofore position and may be detuned with respect to the necessary to accomplish transmission of the signal in another position of rotation. Obviously, energy from the loop to the receiver without the 50 this will result in energy being impressed on the use of continuous leads which may become twistreceiver which is not truly characteristic of the ed or broken. physical position of the loop relative to the source Numerous other objects and advantages will of signalling energy. In addition, owing tothe become apparent from the detailed description low potentials of the loop circuit-such ring-brush which iollows: 55

Briefly, all of the above advantages and objects are attained in accordance with the present invention by the use of a shielded loop aerial mounted on a shaft, which may be driven continuously in any manner. The shaft has mounted thereon the primary of a transformer, the secondary winding of which is located in the field of the primary and coaxial with respect thereto so that a constant coupling between the primary Winding and the secondary winding is maintained at all times irrespective of the. relative rotation between the parts. The transformer windings are matched, or so proportioned to the impedance of the loop and the input impedance of the receiver as to effect the optimum transfer of' energy, as is well-known in the art. The transformer has as nearly as possible. unity coupling, that is to say, it is constructed to give the minimum possible magnetic leakage. A commutator, having a pair of metallic segments connected together and spaced degrees apart on this periphery, is driven in synchronism with the rotation of the shaft. Brushes are located adjacent the periphery of this commutator and adapted to be rotated in such a manner that the brushes may be moved to any angular position on the commutator. The brushes aremoved by means of a handle which cooperates with a, scale, the outer periphery or rim of which has compass markings thereon, and the center of which has a ground glass target. The output of the secondary winding is connected with an amplifier, the output of which feeds a loud speaker connected in series through the brushes referred to above in the output circuit of the amplifier. A rectifier is connected in shunt with the loud speaker winding and feeds a galvanometer having a vibrated reflector. A light source and lens cooperate to throw a beam of light on the reflector at such an angle that the reflected beam will oscillate across the face of the scale under certain conditions. In operation the absorption system is continuously rotated in any manner. The commutator rotates in synchronism therewith. Every time the plane of the loop passes through the line between the loop and the signal source the amplitude of the energy is maximum and sets up an aural indication in the loud speaker and also energizes the rectifier which sends a pulse of unidirectional current to the galvanometer. This pulse oscillates the reflector of the galvanometer and causes the reflected light to move across the face of the scale. By moving the po sition of the brushes on the commutator a position may be reached at which the series circuit through the brushes and loud speaker is com pleted only when the plane of the loop is at right angles to the signalling source. Under these conditions the signal energy impressed on the loud speaker will be zero. Likewise, the energy to the rectifier Will be zero and the movable mirror in the galvanometer will come to rest at a position such that the light beam reflected from the source to the galvanometer mirror and from there to the ground glass center of the scale will come to rest at the center point on the scale, thereby indicating that minimum signal is being received. The pointer on the handle will now indicate on the scale the direction of the signalling source.

The novel features of the invention have been pointed out with particularity in the claims appended hereto.

The nature of the invention and mode ofoperation thereof will be better understood from the detailed description which follows and therefrom when read in connection with the drawings throughout which like reference numerals indicatelike parts and in which:

Figure 1 shows partly diagrammatic and partly schematic the receiver, of the present invention; while Figure 2 shows a preferred form which the invention may take.

Referring to Figure 1 of the drawings, 2 indicates a loop aerial shield mounted for rotation on a shaft 4'. The shaft 4 may be rotated by means of a motor 6 comprising a shaft 7 and a worm 8 cooperating with a worm If] on the shaft 4. The shaft 1 may be mounted in any manner as for example in supports ii. The shaft 4 terminates in a transformer l2 having a primary winding core IS on which a primary winding comprising a number of turns'l4 is mounted. The turns H! of the primary winding are connected by leads as shown with the inductance IS in the shield '2. The secondary winding of the matched transformer l2 comprises a plurality of turns 15 mounted on the core l6 which also serves as a support for the winding. The terminals, of the winding I75 are connected by leads to the grid 3 and cathode IQ of a thermionic tube 25 which is in turn coupled through a transformer 22 to the input electrodes of a second radio frequency amplifier 24 which has its output electrodes connected through a transformer 26 to the input electrodes of a detector 28. It will be understood that more or less amplifiers than are shown maybe, used and that the amplifiers and detectors shown are not meant to limit in any manner the nature of the thermionic relay interposed between the secondary and the loud speaker since it will be understood that any number of amplifiers or a single detector may be used depending on the circumstances under which the receiver is to be used.

The detector 28 has its output electrodes connected through a transformer 30 to the input electrodes of another thermionic repeater 3|, which in turn is connected through a transformer 32 to an amplifier 33. The anode electrode 34 of tube 33 is connected in an output circuit which includesthe winding 35 of an aural indicator as for example a loud speaker, and is completed by way of the brushes 40 and 4| cooperating with the commutator in a manner described more in detail hereinafter to the positive of a source of potential B. A rectifier R is connected by leads 36 and 31 in parallel with the winding 35 of the loud speaker LS. This rectifier may be of any known type and preferably one that comprises copper oxide plates. The output terminals of the rectifier R are connected with the input terminals of a galvanometer G. The galvanometer G which is of relatively low period that is with respect to the number of current pulses per second delivered by the commutator to be described more in detail hereinafter has a moving element 42 which vibrates at an amplitude which is determined by the position of the brushes 40 and on the periphery of the commutator to be described later. A light source 43 cooperates with a lens 44 to direct a beam of light 45 on the movable'element 42' of the galvanometer. This light beam after being reflected by the element 42 is thrown on an indicator scale 46 stationarily mounted on a support 41 coaxial with the commutator which will now be described. A come mutator 58 is mounted on a shaft 5! for rotation in asupport 52 in synchronism with the loop 2. This rotation in synchronism of the loop 2 and commutator '50 mayzbe' accomplishedibyameans of :a flexible' shaft 'i 53. The I brushes an'd14 l :aremounted on supports. 54 .fll'ldii55, respectively to bear-on: the periphery zof the-commutator 250. The members 54 and 55 are supported in turn on a member 56, which may include 'anzopenin'g embracing the shaft 5 I :insuchzza-mannerf that; the brushes are maintained synnnetrically'180;;degrees apart on the periphery'of the commutator 50. The members:.54,a55;an'd:56 arexofzsufiicient weight to prevent rotation thereof due to the friction between the brushes 40: and 4 l :and. the periphery of the -commutator:50. If the weight ofthese elements is insuflicient to preventrotation of the-support and brushes other means not shown-may be'provided; On the periphery of the commutator 50 are located a pair of segments S, the vtwo segments being located 180 degrees apart and being connectedtogether by a connector'58, as indicated-in such a manner that when the brush 4| bears on oneof the pair of segments, and the brush 40 bears on the other of said pair of segments, the circuit between the output electrodes of the tube 33 is completed. The member 54 of the support for the brushes has integral therewith a handle 60 having a pointer 6| cooperating with compass markings -62 on the periphery of the-scale 46. The scale has at the center a ground glass portion 64 on which the beam of light 45 is adapted to fall when the oscillating member 42 of the-galvanometer G-comes torest.

The operation of the'invention' is thought to be'clear from the foregoing detailed description of the invention and from the statement of the operation given hereinbefore.

However, the operation of the receiver will again be repeated.

In operation the loop 2 is continuously rotated. The commutator5ll is rotated in synchronism therewith. If the handle 60 is in such-a position that the indicator. does not indicate the position (usingnull point reception) of the source of signals on" each rotation of the loopeach completion of the circuit through theanode-electrodes of the tube 34 signal energy will flow in the out put circuit. This signal energy acting in the galvanometer Gwil1 vibrate themember -42 and cause the ray of light 45 to oscillate-across the ground glass portion -64 of the scaler45,'thereby indicating that the pointer 6! has not been moved into a position at which the circuit through brushes in the output circuiti-33- is'completed at the same time that the loop 2 is ina position-at which its plane-is at-right angles to thesource of signals-when. the output circuitof :34 is completed. By moving the handle-60 and' pointer 6! toa certain position, such that the circuit through the brushes 4|, 40 is completed when-.the loop 2 is; at right angles to the 'sourcecof: signals, the energy flowing in the output circuit of 35 will be zero, the galvanometer G will not be actuated,

. and the oscillating member 42 will come to rest at a point such that the beam of light 45 will fall on the center of the ground glass portion of 64 of scale indicator 46, thereby indicating the direction of the source of signals.

In Figure 2 a practical application of the receiver has been shown. This modification need not be described other than to point out that the entire apparatus may be ranged in a compact assembly, as shown, andmay be supported by means of a support l0 which, in addition to supporting the entire apparatus, except for the scale, forms a rotatable mounting for the motor 6, 8

aridaa rotatable mountlngi for: the shaft"2,"which mayibebr'oke'n as indicated :at I I and/or atrl2, andrinz addition. forms-the core forthe secondary winding-,otthe matched transformer l2. .The indicator'46 is located coaxial with the commutator 5ll: and below saidxcommutator in a; position to be readily visible to. the operator. The scale 46-has the compass markings on the, outer. upper rim thereof which cooperate with the pointer 6| to indicate the position. of the source of signals. 1

' The.-scale 46 may :be jmounted in any manner,

asyfor. example, by means of supports 12 and .13, asindicated. In this'modification the amplifier has been shown diagrammatically-as has been the loud speaker:LS. The operation, however, 1

of this system is the same. In this modification,

however, the light source 43 and "galvanometer G,-:with moving-element 42, is located below the scale46 so that the reflected light ray 45 falls on the under sidesof the ground glass portion 64 of 2 the} scale 46.

It is obvious that this apparatus maytalso' be used -for direction finding without involving-either continuous rotation ofthe loop or visible indication. By disconnecting, .as by a suitable clutch, 2 the driving means 6, I, 8, and providing-a scale and index for disc 50, manual rotation of disc will rotate loop 2, and the direction ascertained aurally,.as by loudspeaker LS, or the customary head phones.- I'Ihe change from automatic to 3 manual operation cantbe made in a few seconds, and when used manually it'has the advantage of freedom from contact and other troubles inherent in the conventional brush-and slipring.

Having thus described my inventionand the 3 operation thereof, whatI claim is:

.1. The combination ofa rotatable directional radiant absorption member,;a commutator-rotatable in synchronism therewith, an amplifier'coupled with-saidabsorptionmember, a pair. or adjustablebrushes cooperating with said commutator and connected in series with said amplifier output-:zelectrodes tocomplete a circuit between said. output electrodes in adjustable positions of rotation'of said commutator and absorption .mem- 4 her, va-rectifier connected with the output circuit of said iiamplifier, a galvanometer including a movable reflector member connected'with said rectifier,the position of saidrefiector being determined-by the. nature ofthe energy applied to 50 throughsaid commutator is completed.

-2. A-visual direction indicator comprising :a continuously rotatable. loop, a matched transformer having a-primary winding connected with said loopand continuously'rotatable .withsaid loop, arcommutatonhaving apair" of segments 6 on its periphery, means for rotating said commutator in synchronism with said loop, an amplifier having its input terminals connected with the secondary winding of said matched transformer and its output terminals connected in cir- 6 cuit with adjustable brushes cooperating with said commutator, a galvanometer connected with said amplifier output to be energized thereby, said galvanometer having a movable reflector the movement of which depends on the position of 7 said brushes and the position of said loop when said brushes and commutator complete the circuit connected with the output terminals of said amplifier, a light source and a lens adapted to. concentrate a ray of light from said source on 7 said movable element of the galvanometer, and a scale in the path of said ray of light when refiected, said scale having a ground glass portion on which the light ray will fall when said movable element comes to rest, and a pointer fastened to said adjustable brushes and cooperating with said scale to indicate the position at which the circuit through said commutator and brushes is completed.

3. The combination oi. a rotatable directional aerial an amplifier coupled thereto, a commutator which has imparted thereto movements similar to movements which may be imparted to said aerial, a pair of adjustable brushes associated with said commutator and connected with said amplifier output terminals to complete an output circuit for said amplifier in adjustable positions of said commutator, a light source, a scale, means connected to said circuit connected with said amplifier output terminals for controlling the direction taken by the light rays leaving said light source relative to said scale, in accordance with the nature of the energy in said amplifier output circuit, and a pointer connected with said brushes and said scale to indicate the position at'which the circuit connected with said amplifier output electrodes is completed by said commutator and brushes.

4. A visual direction indicator. comprising a movable directional aerial, a matched transformer having a primary winding connected to said aerial and movable with said aerial, a commutator having a pair of segments on its periphery, means for moving said commutator in a manner characteristic of movements of said aerial, an amplifier having its input terminals connected with the secondary winding of "said matched transformer, a circuit connecting the output terminals of said amplifier with adjustable brushes coopcrating with said commutator, a galvanometer connected with said last named circuit, said gal vanometer having a movable reflector the movement of' which is determined by the nature of the energy applied to said galvanometer, a light source and a lens adapted to concentrate a ray of light from said source on said movable element of the galvanometer, and a scale having a recording'portion in the path of said ray of light when reflected and a pointer fastened to said adjustable brushes and cooperating with said scale. 7

5. The combination of a rotatable loop, a commutator rotatable in synchronism therewith, an amplifier coupled to said loop, a pair of adjustable brushes cooperating with said commutator and connected in series with said amplifier output circuit, an impedance in said output circuit, a rectifier connected in parallel with said impedance, a galvanometer connected with said rectifler, said galvanometer controlling the position 01 a reflecting element, a light source and a scale associated with said reflecting element, and a pointer cooperating With=Said scale to indicate the position of said brushes relative to said comindication, an amplifier having its input termil5 nals connected in series with the secondary windingof said matched transformer and its output terminals connected in series with said brushes, a rectifier connected with said output circuit, a

galvanometer connected with said rectifier, said galvanometer having a movable reflector, the positionof which is determined by the amplitude of the energy fed from said output circuit to said rectifier, a light source and a lens adapted to concentrate a ray of light from said source'on said 25.-

movable element of the galvanometer, and a scale member having a translucent portion in the path of said ray of light when reflected, and having graduations against which the position of said brush holder may be registered.

7. A directional receiving system comprising a directive absorption member, the position of which may be moved relative to a source of signalling energy to vary the amount or energy absorbed by said member, a thermionic relay having its 35.

input electrodes coupled to said member and its output electrodes coupled to a normally opencircuit, a commutator connected to said absorption member for movement therewith, adjustable brushes connected with said output circuit and 40 cooperating with said commutator to close said output circuit in pre-determined positions 01! movement of said absorption member and commutator, which positions may be changed by ad justing the position of said brushes, a galvanometer connected to said output circuit to be energized thereby when said circuit is closed, said galvanometer having a movable reflector which is moved from a zero position, when said output circuit isclosed, an amount determined by the amplitude of the energy in said output circuit, a scale having a ground glass portion on which light reflected from said reflector in a zero position I falls and a pointer connected with said brushes and cooperating with said scale, to indicate the position of said brushes when the energy in said output circuit when completed is not suificient to cause said reflector to leave its normal zero position.

GREENLEAF WHITI'IER PICKARD. 

